Scientists Find Way to Send Passwords via Human Body
A new technique devised by a team of researchers at the University of Washington leverages the signals already generated by fingerprint sensors on smartphones and laptop touchpads to transmit data through the human body.
“Fingerprint sensors have so far been used as an input device. What is cool is that we’ve shown for the first time that fingerprint sensors can be re-purposed to send out information that is confined to the body,” said team member Dr. Shyam Gollakota, a researcher with the Department of Computer Science and Engineering at the University of Washington.
Dr. Gollakota and his colleagues, Mehrdad Hessar and Vikram Iyer, tested the technique on iPhone and other fingerprint sensors, as well as Lenovo laptop trackpads and the Adafruit capacitive touchpad.
In tests with ten different subjects, they were able to generate usable on-body transmissions on people of different heights, weights and body types.
The system also worked when subjects were in motion — including while they walked and moved their arms.
“We showed that it works in different postures like standing, sitting and sleeping,” Iyer said.
“We can also get a strong signal throughout your body. The receivers can be anywhere — on your leg, chest, hands — and still work.”
The researchers analyzed smartphone sensors to understand which of them generate low-frequency transmissions below 30 MHz that travel well through the human body but don’t propagate over the air.
They found that fingerprint sensors and touchpads generate signals in the 2 to 10 MHz range and employ capacitive coupling to sense where your finger is in space, and to identify the ridges and valleys that form unique fingerprint patterns.
Normally, sensors use these signals to receive input about your finger. But the scientists devised a way to use these signals as output that corresponds to data contained in a password or access code.
When entered on a smartphone, data that authenticates your identity can travel securely through the human body to a receiver embedded in a device that needs to confirm who you are. Their process employs a sequence of finger scans to encode and transmit data.
“We show that commodity fingerprint sensors and touchpads can be used to generate wireless data transmissions that are confined to the human body,” the researchers said.
“We present a receiver design that can reliability decode our data transmissions and demonstrate bit rates of up to 50 bps by modulating the operations of these input devices.”
The scientists presented their results September 16 at the 2016 Association for Computing Machinery’s International Joint Conference on Pervasive and Ubiquitous Computing in Heidelberg, Germany.
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